Simon Reeve finishes his journey around the Tropic of Cancer in Hawaii, where he discovers that the paradise islands are the extinction capital of the world, with more species dying-out than anywhere else on the planet. Several of Hawaii’s beaches are also covered in plastic rubbish washed-up from the Great Pacific Garbage Patch (a vast accumulation of the world’s plastic debris floating in the Pacific Ocean). Hawaii is the world’s most isolated island-chain, and the only tropical region of the richest country on earth. But there are enormous quantities of plastic debris on many beaches, and the plastic is breaking-down into smaller and smaller fragments the size of sand granules, making it impossible to remove. As Simon finishes his journey he wonders: if the US government can’t protect the environment in Hawaii, what hope is there for poorer countries throughout the Tropics?